[A case of fatal cocaine overdose]. / Intoxication mortelle à la cocaïne.

Clinical, biological, and therapeutic description of a lethal case of cocaine overdose.

Magnesium--a profibrillatory or antifibrillatory drug depending on plasma concentration, heart rate and myocardial perfusion.

BACKGROUND: The opinions on the efficacy of magnesium as an antiarrhythmic drug vary considerably. The action of magnesium on vulnerability to fibrillation was therefore investigated in anaesthetized, open-chest pigs under different conditions as regards plasma concentration, heart rate and myocardial perfusion. METHODS: Vulnerability to fibrillation was assessed by electrical fibrillation threshold (EFT), measured with 100-ms duration diastolic impulses. These stimuli were delivered to the heart normally perfused, at a usual (90 and 120 beats/min) or accelerated (180 beats/min) rate. Vulnerability to fibrillation was also assessed at the high rate (180 beats/min) in the heart made ischaemic by complete occlusion of the left anterior descending coronary artery near its origin. EFT was then measured at the end of occlusion periods which were of increasing duration (30, 60, 90, 120 s). Monophasic action potential (MAP) duration, intraventricular conduction time, left ventricular dP/dt max (LVdP/dt max) and mean blood pressure were concurrently measured. RESULTS: In the absence of ischaemia, 5 mumol.kg-1.min-1 magnesium i.v. infusion, which raised plasma concentration to 1.78 +/- 0.14 mmol/L, lowered EFT, measured at the rate of 116 beats/min, from 14.0 +/- 1.1 to 6.8 +/- 1.0 mA (P < 0.001), without significant variation of the other parameters. Administered as previously or in a markedly higher dose (400 mumol.kg-1 loading dose and 10 mumol.kg-1.min-1 infusion) which raised plasma concentration up to 4.84 +/- 0.52 mmol/L, magnesium significantly influenced neither EFT nor MAP duration, reduced by the high rate (180 beats/min) to 6.2-6.7 mA and 212-220 ms respectively. Under the same conditions, at the same 180 beats/min rate, ischaemia brings about a fall of EFT, from 6.9 down to nearly 0 mA, with occurrence of fibrillation, in approximately 120 s. Magnesium failed to slow this fall and to delay the onset of fibrillation. In contrast, within the minutes following the end of occlusion, magnesium increased EFT to a great extent (from 7.1 +/- 0.4 to 13.5 +/- 0.7 mA, P < 0.001), with a significant prolongation of MAP duration (212 +/- 6 to 234 +/- 8 ms, P < 0.01). CONCLUSION: Magnesium may develop profibrillatory or antifibrillatory effects depending on plasma concentration, heart rate and myocardial perfusion.

[Immunonephelometric analysis of immunoglobulin light chains: agreement between the theoretical and experimental model. Assessment of the reference values of the kappa/lambda ratio and the heavy to light chain ratio]. / Dosage immunonéphélémétrique des chaînes légères d'immunoglobulines: concordance du modèle théorique et du modèle expérimental. Détermination des valeurs de référence des rapports kappa/lambda et chaînes lourdes/chaînes légères.

Since the introduction of fully automated nephelometric systems simultaneous measurements of immunoglobulin light chains kappa (kappa) and lambda (lambda) and IgG, IgA and IgM have become increasingly used for the routine assessment of humoral immunity. From these data two ratios were calculated, the kappa/lambda ratio and the heavy chains to light chains ratio. As changes in these ratios might have some predictive clinical value besides reflecting a monoclonal component, it is necessary to know mean and reference limits of these ratios. On account of differences in the calibration method of the light chains measurements (either free light chains or light chains bound to a complete molecule) and of differences in the calculation method of the heavy chains to light chains ratio we were led to conduct our own investigation. IgG, IgA and IgM and kappa and lambda light chains were immunonephelometrically measured in the sera of 84 blood donors. For each sample theoretical values for kappa + lambda, kappa and lambda, and kappa/lambda were calculated using the existing relation between the concentration of a given immunoglobulin and the concentration of bound light chains. Using the Valtec Protocole and the t test we were able to evidence highly significant differences (p < 10(-4) between theoretical and experimental values of kappa, lambda and kappa + lambda; those differences could be proved to be directly linked to the nephelometric technique itself. However the experimental kappa/lambda ratio did not appear to differ from the theoretical one nor the standardization method to have an effect on the reference values of this ratio, our values (mean and reference limits, 1.81, 1.29-2.53) being very similar to previously published results. Concerning the so called heavy chains to light chains ratio two methods were used to express it, one consisting in the ratio of the theoretical kappa + lambda value to the experimental one with the following results, 1.05 and 0.93-1.18 for the mean and reference limits and the other one using the raw data. The results were as follows: mean 3.50, reference limits 3.11-3.94.

[Value of a new fast CK-MB determination for the diagnosis of myocardial infarction during the 1st hours. Preliminary study]. / Intérêt d'un nouveau dosage rapide de la CK-MB pour le diagnostic de l'infarctus du myocarde dans les premières heures. Etude préliminaire.

This study evaluated the time for a new, rapid and reliable CK-MB analysis to become positive in myocardial infarction and compared it with classical total CK analyses. Serial analyses of total CK and CK-MB were performed in 49 consecutive patients referred to the Coronary Care Unit for suspected acute myocardial infarction. Twenty of these patients had myocardial infarction with rising enzyme levels, which enabled comparison of the precocity of one analysis compared to another. In these patients, the CK-MB analysis became positive on average 85 to 110 minutes before that of total CK. This result shows that CK-MB analysis can be a diagnostic sign of acute myocardial infarction at an earlier stage than the total CK analysis. The authors discuss the clinical value of this test in difficult indications of fibrinolytic therapy and underline that it enables a more objective assessment of the time of onset of necrosis than clinical data alone.

[Accuracy in thyroid hormonology: evaluation of free T4 by five immunometric methods using cold markers]. / Exactitude en hormonologie thyroïdienne: dosage de la T4 libre par cinq méthodes immuno-métriques avec marquage froid.

During a comparative multicentric evaluation, five commercially available non-isotopic methods for FT4 measurement were tested. As with the radioactive methods the problem with accuracy is again evident. This is true both for setting reference values and standards as well as for the specificity of the methods. The authors demonstrated highly significant correlations as described in recent papers: many of the values may, however, be up to double value in one center compared to another despite the correlation of 0.90.

[Assay of digoxin on dry-reagent strips]. / Dosage de la digoxine sur supports de réactifs secs.

An automated immunoassay for Digoxin in serum using dry-reagent strips (Stratus Dade) was evaluated, and compared with two others immunoassays (TDX Abbott and ACA Du Pont). Precision, sensitivity and specificity were satisfying, as well as correlation study, but discrepancies observed for some sera proved that these techniques still pose serious problems of specificity or of standardisation.

[Electrophoresis of urinary proteins on SDS-polyacrylamide gel, without preliminary concentration]. / Electrophorèse des protéines urinaires en gel de polyacrylamide-SDS sans concentration préalable.

We described a rapid and sensitive method for urinary proteins disc-electrophoresis on unconcentrated urine, by using polyacrylamide-SDS gel in discontinuous gradient. Correlation with a conventional polyacrylamide agarose slab electrophoresis on concentrated urine is good, our technique being more sensitive when proteinuria is low. It had proved to be useful for routine detection of renal failures in clinical laboratories.

[Physicochemical changes in hemoculture media related to blood]. / Modifications physicochimiques des milieux d'hémoculture liées à l'apport de sang.

Inoculation of sterile blood into a blood culture medium causes changes of some physicochemical properties, whose maintenance is necessary for growth of fastidious micro-organisms. During incubation of these media at +37 degrees C, red cells utilize glucose for their metabolism, causing acidification and increase of carbon dioxide partial pressure, while oxygen partial pressure tends to decrease during first days of incubation, and increase after. Experimental conditions (choice of medium, volume of blood incubates, ventilation, glucose concentration) notably modify these results. This work underlines the necessity for a greater standardization of media and of technical conditions, in execution of blood cultures.

[Determination of certain physico-chemical parameters in blood culture media]. / Intérêt de la détermination de certains paramètres physico-chimiques des milieux d'hémoculture.

Growth of delicate or exacting microorganisms needs the maintenance, in the culture medium, of precise and stable physicochemical conditions. In order to improve knowledge of these medium, and specially of their aerobic or anaerobic state, we measured pH, partial pressures for oxygen and carbon dioxide and glucose concentration of nine commercial blood culture media, in their natural conditions of use. Comparative study of experimental results, and study of successive fabrication lots of two of these media (brain-heart and Schaedler) reveals a great variability of physicochemical parameters, and specially of pO2 and glucose concentration, although initial composition of the media has theoretically not changed. It would be desirable that such parameters be better controlled, so as to encourage regularity of composition of blood culture media and, perhaps, their clinical efficiency.

Laser nephelometry and radial immunodiffusion compared for immunoglobulin quantification in pathological sera.

We evaluated nephelometers from Behring, Hyland, and Beckman for IgG, IgA, and IgM quantitation in sera from patients with monoclonal gammopathies. The intra-batch precision of each instrument for each immunoglobulin class and for different concentrations of the same immunoglobulin was compared to the one obtained with the radial immunodiffusion method. No nephelometer showed a clearly better precision. The correlation with cellulose acetate electrophoresis was good for each of the three nephelometers. The mean value by the radial immunodiffusion method was higher than corresponding determinations by nephelometry.

[The estimation of fibrinogen by kinetic immunonephalometry]. / Dosage du fibrinogène par immunonéphélométrie cinétique.

A new immunonephelometric micromethod for the estimation of fibrinogen is described. The reaction, linear between 0.30 g/l and 11 g/l requires only 5 microliters of plasma. The precision and sensitivity of the method are satisfactory. Comparisons with the chronometric technique of Clauss and with the Mancini immunodiffusion technique were made.